Designing Food Chains and Food Webs

Transcription

1 Designing Food Chains and Food Webs NGSSS: SC.912.L.17.9 Use a food web to identify and distinguish producers, consumers, and decomposers. Explain the pathway of energy transfer through trophic levels and the reduction of available energy at successive trophic levels. AA (Also addresses SC.912.E.7.1, SC.912.L.17.10) Background: (Source: All organisms in an ecosystem need energy to survive. This energy is obtained through food. Producers obtain energy by making their own food whereas consumers must feed on other organisms for energy. This dependence on other organisms for food leads to feeding relationships that interconnect all living things in an ecosystem. A food chain illustrates the simplest kind of feeding relationship. For example, in a forest ecosystem, a grasshopper feeds on plants. The grasshopper is consumed by a spider and the spider is eaten by a bird. Finally, that bird is hunted by a hawk. A food chain clearly shows this pathway of food consumption. You could probably think of another food chain for a forest ecosystem. In fact, many different food chains exist in ecosystems. Although there are many different kinds of food chains, each food chain follows the same general pattern. A link in a food chain is called a trophic, or feeding level. The trophic levels are numbered as the first, second, third, and fourth levels, starting with the producers. Each of the trophic levels is occupied by a certain kind of organism. Producers are always in the first trophic level since they do not feed on another organism. Consumers occupy the rest of the trophic levels. The second trophic level is the first consumer in the food chain and is called a primary consumer. Primary consumers eat plants and are therefore herbivores or omnivores. The next consumer in the food chain is the secondary consumer. The secondary consumer is in the third trophic level. Since the secondary consumer feeds on another animal, it is a carnivore or an omnivore. Similarly, the tertiary consumer occupies the fourth trophic level, and is a carnivore. The last link in a food chain is also referred to as the top carnivore since it is at the top of the food chain and is not hunted by other animals.

2 Problem Statement: Are food chains and food webs the same? How do organisms transfer energy? Vocabulary: food chain, food web, producer, consumer, decomposer, energy transfer, trophic level Materials (per group): butcher paper or poster paper markers Procedures: You will use the cards below and the information on the cards to construct a food web. Please follow the checklist below to demonstrate mastery of this standard. Your grade will be determined as follows: 1. Number of Organisms a. 4 producers b. 3 primary consumers c. 2 secondary consumers d. 1 tertiary consumer 2. Method of nutrition identified for each organism a. Autotroph or Heterotroph b. Herbivore, Carnivore, or Omnivore 3. Type of consumer identified if necessary a. Primary b. Secondary c. Tertiary 4. Organisms are arranged according to proper trophic levels. 5. Arrows indicate the direction of energy transfer a. Must be in the proper direction b. Must be easy to follow c. Must be correct according to the information provided on each card Results/Conclusion: 1. Explain what would happen if all of the primary consumers became extinct. 2. Predict what would happen if a non-native species is introduced into the food web. 3. Explain why food webs with many species (biodiverse) are more resilient than those with few species. 4. In theory, the earth could support many more people if we ate at a lower trophic level. a. List 2 benefits of doing this. b. List 2 drawbacks of eating lower on the food chain. 5. Large predatory fish usually are found at the 3 rd or 4 th trophic level of an energy pyramid. What does this mean in terms of energy loss?

3 Assessment Activity Self-Assessment Teacher Assessment Number of Organisms 1 point for each correct organism 10 Total Method of Nutrition 1 point for each correctly labeled organism 10 Total Type of Consumer 2 points for each correctly labeled consumer 12 Total Proper Arrangement 1 point for each properly placed organism 10 Total Arrows All arrows in proper direction 10 pts Easy to follow 5 pts Correct according to card 10 pts Results/ Conclusion 2 points for each correctly answered question Total: /77 Total: /77 Comments:.

4 Bee Nectar from: Poppy, wild rose, berry Produces: Honey Aphid Wild rose, poppy, berry Millipede Grass, Fruit Produces: Compost Raccoon Praying Mantis, Millipede, Butterfly, Berry, Worm, Fruit Grasshopper Fruit, Grass Hawk, Butterfly, Spider Bear Fox Hawk Berry Honey California Blackberry Needs nutrients from the soil. Produces energy by photosynthesis. Berries Fruit Grass Tarantula Cockroach Worm Butterfly Grasshopper

5 California Native Grass Needs nutrients from the soil. Produces energy using photosynthesis. Praying Mantis Aphid Grasshopper Ladybug Aphid Deer Poppy Wild Rose Grass Wild Rose Needs nutrients from the soil. Produces energy using photosynthesis. Mosquito Eats blood from: Deer Raccoon Rabbit Cockroaches Fruit Nutrients from the soil. Worm Fruit and Grass Produces: Soil

6 Fox Hawk Butterfly Berry Tarantula Butterfly Poppy nectar, Fruit California Poppy (nectar) Needs: Nutrients from the soil. Produces energy using photosynthesis Fruit Flower Produces pears Gets nutrients from the soil. Produces energy using photosynthesis.